1. Field of the Invention
Low-sling additives for fiber lubricants, especially coning oil type lubricants, are well-known in the art as protective coatings for fibers in a variety of textile operations. Many of these additives, particularly relatively low molecular weight polymers such as polyisobutylene, are in common use to improve adherence of the lubricant to the fiber and reduce lubricant "sling-off" during yarn winding operations.
2. Discussion of Related Art
While these additives have proved generally useful in lubricants for low-to-medium speed fiber winding operations (for example, for yarn speeds up to about 500 meters/minute), in ultra high speed winding operations conventional low molecular weight polyisobutylene and comparable low-sling polymer additives have not sufficed to reduce lubricant slign-off to acceptable levels. Further, these known additives are not uniformly reliable and tend to perform erratically under varying process parameters, particularly with respect to fiber type, yarn speed, machinery characteristics, processing temperatures, and recirculation conditions. For general commercial acceptability, it is important that fiber lubricants for man-made fibers reduce friction between the yarn and contact surfaces, for example surfaces of processing machinery or interfaces with other fibers; adhere to the yarn to reduce sling-off during processing; and be scourable to permit substantially complete removal before downstream operations such as dyeing and finishing, with which lubricant residue would substantially interfere. It is particularly important that lubricant compositions consistently function well to perform these tasks under a variety of operating conditions, in order to obviate the necessity of reevaluating and reformulating each lubricant composition on an ad hoc basis.
The invention accordingly provides a high-tack fiber lubricant which has broad applicability and which exhibits low-sling characteristics over a broad range of fiber types, lubricant add-on requirements, and yarn processing conditions. Lubricants according to the invention are especially useful in ultra high speed winding operations, particularly those involving yarn speeds in excess of about 700 meters/minute, wherein lubricant sling-off is minimized while adequate fiber lubrication and scourability are maintained.
The lubricant composition of the invention comprises ultra high molecular weight oil-soluble polyisobutylene in a mineral oil vehicle with sufficient emulsifier to ensure a storage stable, uniform composition, which is readily scoured from the fiber. The composition further optionally includes customary lubricant additives such as antistatic agents to reduce static charge build-up fibers during processing, and corrosion inhibitors to protect vulnerable machine component parts. Compounding and handling conditions must be strictly observed to maintain consistent product performance. In particular, it has been found to be critical to avoid shear of sufficient force to disrupt polymer integrity during product handling, especially during formulation of the composition. Mixing and circulation/recirculation operations involving strong agitation, mechanical pumping, or operations inducing similar product stress, such as filtration, are thus to be avoided.